In British Patent Specification No. 883013, there are described a number of N,N'-disubstituted piperazines which are stated to have atropinic, anti-histaminic, spasmolytic, anti-emetic and anaesthetic activities.
Surprisingly, it has now been found that a number of diamine derivatives, including those described in British Patent Specification No. 883013, as described in formula I, are active in restoring drug-sensitivity to cancer cells that have become multidrug-resistant. Such compounds, therefore are useful as adjuvants in oncology.